Additive and a catalyst composition comprising the additive for FCC process

ABSTRACT

The present disclosure relates to an additive and a catalyst composition for a catalytic cracking process of vacuum gas oil for preparing cracked run naphtha having reduced liquid olefin content, and increased propylene and butylene yields in the LPG fraction. The process makes use of a catalyst composition which is a mixture of an FCC equilibrated catalyst and an additive comprising a zeolite, phosphorus and a combination of metal promoters. The process is successful in achieving high propylene and butylene yields in the LPG fraction along with a lower liquid olefin content and increased aromatic content with increase in RON unit in the resultant cracked run naphtha, as compared to that achieved using an FCC equilibrated catalyst alone.

FIELD

The present disclosure relates to an additive for a catalyst compositionfor a fluid catalytic cracking process.

Definition

As used in the present disclosure, the following word/phrase isgenerally intended to have the meaning as set forth below, except to theextent that the context in which it is used indicates otherwise.

FCC EQUILIBRATED CATALYST (ECAT): ECAT is a “used/spent” catalyst,containing at least some of the catalyst charged originally. ECAT isused in the petroleum refining industry to convert crude oil fractionsinto smaller molecular weight hydrocarbon compounds.

BACKGROUND

Vacuum distillation of crude oil results in a variety of petroleumproducts with a wide range of molecular weights. The heavier hydrocarbonfractions, usually, the left-overs from the vacuum distillation processare converted and refined into more valuable lower molecular weighthydrocarbons with the help of a fluid catalytic cracking (FCC) unit. Theever-increasing demand for gasoline has seen a surge in such refiningunits.

Vacuum Gas Oil (VGO), a component of the heavier hydrocarbons, issubjected to cracking in an FCC unit, resulting in cracked run naphtha(CRN), fuel oil and offgas as the end-products. The cracked run naphtha(CRN) produced by the cracking of VGO, typically, contains around 45% to55% liquid olefins. When these liquid olefins come in contact withdissolved oxygen, they form hydro peroxides as immediate products, whichundergo further reactions to form insoluble oxidized species. Theseoxidized species that include peroxides, aldehydes, acids, ketones aswell as components with molecular weights 200 to 600 g/mol are commonlyreferred to as gum. This insoluble gum formation in the interior of theprocess units results in fouling. Although, rigorous exclusion of oxygenor the addition of anti-oxidants are enough to eliminate fouling, insome industrial situations oxygen ingress cannot be easily prevented. Ifthe liquid olefin content in the CRN is brought down, the gum formationand hence, fouling can be controlled.

Also, the demand for propylene is more as compared to the other crackedproducts. Various attempts have been made to increase the yield ofpropylene during cracking. Attempts have been made in the past toimprove both the FCC process and the catalyst used in the FCC process.Though, an increase in the propylene yield was observed, the amount ofpropylene obtained was still low (typically less than 6%).

Thus, there is a felt need to increase the propylene yield and reducethe liquid olefin content simultaneously in a fluid catalytic crackingprocess.

OBJECTS

Some of the objects of the present disclosure, which at least oneembodiment herein satisfies, are as follows.

It is an object of the present disclosure to ameliorate one or moreproblems of the prior art or to at least provide a useful alternative.

An object of the present disclosure is to provide an additive for acatalyst composition for a fluid catalytic cracking process.

Another object of the present disclosure is to provide a catalystcomposition for a fluid catalytic cracking process.

Still another object of the present disclosure is to provide a fluidcatalytic cracking process.

Yet another object of the present disclosure is to provide a fluidcatalytic cracking process to obtain a product having an increasedpropylene yield, an increased butylene yield, reduced liquid olefincontent and reduced coke content.

Other objects and advantages of the present disclosure will be moreapparent from the following description, which is not intended to limitthe scope of the present disclosure.

SUMMARY

In accordance with an aspect of the present disclosure there is providedan additive for a catalyst composition for a fluid catalytic crackingprocess. The additive comprises a zeolite impregnated with phosphorus inthe range of 10 wt % to 15 wt % with respect to the weight of thezeolite and a combination of metal promoters comprising nickel, andcalcium, independently in the range of 0.5 wt % to 2.0 wt % with respectto the weight of the zeolite. The “Phosphorus” promoted zeolite isspray-dried and the formulation is loaded with the metal promoters.

A catalyst composition comprising an FCC equilibrated catalyst (ECAT) inthe range of 80 wt % to 99 wt % and an additive in the range of 1 wt %to 20 wt %, for a fluid catalytic cracking process is also provided inthe present disclosure.

The present disclosure further provides a fluid catalytic crackingprocess for obtaining a product having increased propylene yield,increased butylene yield, decreased liquid olefin content and reducedcoke content, using a catalyst composition. The catalyst compositioncomprises an FCC equilibrated catalyst (ECAT) and an additive.

DETAILED DESCRIPTION

The present disclosure will now be described with reference to theaccompanying embodiments which do not limit the scope and ambit of thedisclosure. The description provided is purely by way of example andillustration.

The embodiments herein and the various features and advantageous detailsthereof are explained with reference to the non-limiting embodiments inthe following description. Descriptions of well-known components andprocessing techniques are omitted so as to not unnecessarily obscure theembodiments herein. The examples used herein are intended merely tofacilitate an understanding of ways in which the embodiments herein maybe practiced and to further enable those of skill in the art to practicethe embodiments herein. Accordingly, the examples should not beconstrued as limiting the scope of the embodiments herein.

The present disclosure in an aspect relates to an additive for acatalyst composition for a fluid catalytic cracking process. Theadditive comprises a zeolite impregnated with phosphorus in the range of10 wt % to 15 wt % with respect to the weight of the zeolite and acombination of metal promoters comprising nickel, and calcium,independently in the range of 0.5 wt % to 2.0 wt % with respect to theweight of the zeolite.

In an exemplary embodiment of the present disclosure, the amount of thephosphorous in the zeolite is 12 wt %, with respect to the weight of thezeolite. The precursor of phosphorus is at least one selected from thegroup consisting of phosphoric acid, phosphates, phosphorous acid,phosphites, pyrophosphoric acid, pyrophosphates, polymeric phosphoricacid, polyphosphates, metaphosphoric acid and metaphosphates.

In an exemplary embodiment of the present disclosure, the amount of themetal promoters with respect to the weight of the zeolite is: 1 wt %nickel 0 and 1 wt % calcium.

In accordance with the embodiments of the present disclosure, theprecursor for each of the metal promoter is a salt of the metal. In anexemplary embodiment of the present disclosure, the precursor of themetal promoter is a nitrate salt of the metal.

The zeolite is at least one selected from the group consisting of ZSM-5,ZSM-11, ZSM-12, ZSM-48, ZSM-57, SAPO-5, SAPO-11, SAPO-17, SAPO-18,SAPO-34, SAPO-44, MCM-22, ZSM-Y and zeolite-beta.

The present disclosure, in an embodiment provides a catalyst compositionfor a fluid catalytic cracking process. The catalyst compositioncomprises an FCC equilibrated catalyst (ECAT) and an additive asdescribed hereinabove.

In accordance with the embodiments of the present disclosure, the FCCequilibrated catalyst (ECAT) is present in the range of 80 wt % to 99 wt% of the catalyst and the additive is present in the range of 1 wt % to20 wt % of the catalyst composition.

In an exemplary embodiment, the FCC equilibrated catalyst (ECAT) and theadditive are present in the ratio of 93:7 wt %. In another exemplaryembodiment, the FCC equilibrated catalyst (ECAT) and the additive arepresent in the ratio of 85:15 wt %.

The catalyst composition is used for a fluid catalytic cracking (FCC)process for obtaining a product having an increased propylene yield,increased butylene yield, reduced liquid olefin content and reduced cokecontent. In the conventional catalytic cracking process, whileprocessing a vacuum gas oil feedstock an FCC equilibrated catalyst(ECAT) is used which yields propylene, typically, less than 6% and theresultant cracked run naphtha has significant liquid olefin content. Inparticular, the present disclosure relates to a process that makes useof an additive in combination with an FCC equilibrated catalyst (ECAT),the mixture thereof increases the propylene yield above 7%, increasesthe butylene yield and reduces the liquid olefin content.

In an embodiment of the present disclosure, an FCC process for obtaininga resultant product having a propylene yield in the range of 7% to 16%,butylene yield in the range of 8% to 10%, liquid olefinic content in therange of 10% to 45% and coke content in the range of 2% to 7%, fromvacuum gas oil, is disclosed. The catalytic reactor, i.e., a fixed fluidbed micro reactor unit (ACE unit) is supplied by M/s KayserTechnologies, Inc, Houston, USA.

The cracking reactions are carried in the temperature range of 400° C.to 700° C. and at a pressure ranging from 1 atm to 2 atm. In anexemplary embodiment, the reactor is maintained at 530° C. and 1 atmpressure.

The feedstock is vacuum gas oil (VGO) obtained as a left-over from thevacuum distillation of crude oil. An inert gas, a non-limiting exampleof which is nitrogen, is selected as a carrier gas. The VGO is contactedwith a catalyst composition comprising an FCC equilibrated catalyst(ECAT) and an additive comprising a zeolite impregnated with phosphorusand metal promoters comprising a combination of nickel, and calciumindependently in the range of 0.5 wt % to 2.0 wt % with respect to theweight of the zeolite.

The resultant product obtained has a propylene yield in the range of 7%to 16%, butylene in the range of 8% to 10%, liquid olefin content in therange of 10% to 45% and coke content in the range of 2 to 7%.

The present disclosure is further described in light of the followingexperiments which are set forth for illustration purpose only and not tobe construed for limiting the scope of the disclosure. The followinglaboratory scale examples performed in the ACE-MAT testing unit can bescaled up to industrial/commercial scale.

Examples

Catalytic cracking experiments were carried out in a fixed fluid bedmicro reactor unit (ACE unit) supplied by M/s Kayser Technologies, Inc,Houston, USA. The cracking reactions were performed at a temperature of530° C. and at a pressure of 1 atm and a constant injection time of 30seconds. The catalyst/vacuum-gas-oil ratio was varied from 3 to 6 wt/wt.

The gaseous products were analyzed using Inficon 3000 micro-GC & Liquidproducts were analyzed by ASTM 2887 in LT SIMDIS supplied by ACAnalytical Controls. The liquid products considered were Gasoline (C5 at221° C.), LCO (from 221-370° C.) & Bottoms (above 370° C.).Prefrac-PIONA analysis of the liquid samples was carried out using PIONAanalyzer and PAC instruments. The conversion was calculated as the sumof the yields of dry gas, LPG, Gasoline and coke.

Catalyst:

The base catalyst used in the cracking reactions was commercial FCCequilibrated catalyst (ECAT). Additives of the present disclosure werestudied at 7 wt % and 15 wt % with the base ECAT. The typicalequilibrated catalyst ECAT properties are listed in Table-1.

TABLE 1 Properties of commercial equilibrated catalyst (ECAT) AttributeFCC ECAT Physical Analysis Surface area, m²/g 135 Pore volume (PV), cc/g0.31 Zeolite surface area (ZSA), m²/g 74 Matrix surface area (MSA), m²/g61 % Crystallinity 11.4 Metals, ppm Ni 2000 V 1350 Na 0.29 Fe 0.28 Sb180 Chemical Analysis, wt % Rare earth, wt % 1.75 Al₂O₃, wt % 52.1 P₂O₅,wt % 0.43Feedstock:

The feed used in the present disclosure was vacuum gas oil (VGO). Thedetail properties of the feed are listed in Table-2.

TABLE 2 Properties of the feedstock Properties VGO Density at 15° C.,g/cc 0.915 Sulphur, wt % 2.0 CCR, wt % 0.60 Pour point, ° C. 45Kinematic viscosity @100° C., cSt 7.742 ASTM-7169 Distillation, wt %Initial Boiling Point (IBP) 283 5 345 10 365 30 404 50 429 70 457 90 50695 529 Metals, ppm Ni 1.0 V 0.9 Na 1.05 Fe 1.35 SARA, wt % Saturates57.1 Aromatics 33.3 Resins 9.4 Asphaltenes 0.2Preparation of the Additive and the Catalyst of the Present Disclosure:

ZSM-5 with a SiO₂/Al₂O₃ mole ratio of 23 was used as the zeolite for theadditive. 10 g of ZSM-5 sample was mixed with varying quantities ofortho phosphoric acid solution and a metal salt solution, especially, ametal nitrate solution to form slurry. The resultant slurry was agitatedthoroughly at 25° C. for 3 hours for allowing phosphorus and the metalsto impregnate the zeolite followed by heating in a rotary evaporatormaintained at 75° C. under vacuum to obtain a dried mass. The dried masswas calcined at 550° C. for 5 hours and finally ground to obtain anadditive powder.

The additive powder was mixed with binder/matrix such as alumina (suchas hydrated alumina, gamma alumina, alpha alumina, and psuedoboehmite),fillers such as clay (bentonite, saponite, montmorillonite, kaolin,smectite, etc.). The ratio of active zeolitecomponent:Binder/matrix:filler is: 40:50:10 (wt %). The additive powder,binder/matrix and filler were mixed in water to obtain a slurry. Theslurry was spray dried to obtain particles having a size of 100micrometers. The spray dried particles were then calcined at 600° C. for5 hours to obtain the additive of the present disclosure which is usedin the FCC process.

The final catalyst additive formulation contained the metal promoters inboth zeolite and binder/matrix. Thus, the whole formulation was activein the FCC cracking process producing higher propylene content and lowerolefins content in the resultant product.

FCC ECAT was mixed with this additive powder in ratios ranging from80:20 to 99:1 wt % and was used as catalyst.

In the case of a mixture of metals, all the metal salts were weighedaccordingly and dissolved in the required amount of water together.

The additives were loaded with phosphorus and metal promoters, accordingto the following

TABLE 3 Metal loading on ZSM-5 “P” Loading with respect to Promotertotal zeolite Metal Promoter Loading name content on zeolite MM3 12% 1%Ni and 1% Ca

Example 1: Catalytic Cracking with FCC ECAT (Comparative Example)

Catalytic cracking of VGO was carried out with 100% FCC ECAT at areactor temperature of 530° C., constant injection time of 30 secondsand catalyst/vacuum-gas-oil ratios of 3.0, 3.9, 4.8 and 6 wt/wt.Propylene yield obtained using ECAT is in the range of 6 to 7 wt % for avarying catalyst/vacuum-gas-oil ratio. Table 4 gives the composition ofthe resultant cracked run naphtha obtained.

TABLE 4 Product composition from Example 1 Catalyst ECAT Feed VGOCracking Temperature, 530.0 530.0 530.0 530.0 ° C. Catalyst to vacuum-3.00 3.90 4.80 6.00 gas-oil ratio, wt/wt Conversion, wt % 69.73 73.1875.56 77.93 YIELDS, wt %: Coke 3.39 4.40 5.05 6.48 Dry Gas (H₂, C₁-C₂)2.60 2.90 3.16 3.50 LPG 19.29 21.19 21.96 23.33 Propylene 6.13 6.55 6.666.87 Butylenes 7.28 7.42 7.30 6.98 Gasoline (C₅-216° C.) 44.45 44.6845.39 44.62 LCO (216-370° C.) 19.23 18.32 16.83 15.52 Unconverted (above10.80 8.73 7.61 6.55 370° C.) % Liq. Olefins 32.00 27.00 25.00 20.02 %Reduction of liq. 0 0 0 0 Olefins % Aromatics 32.89 37.49 39.65 45.79 %Increase in 0 0 0 0 Aromatics RON 94.9 96.1 97.2 98.4 Increase in RONUnits 0 0 0 0

Example 2: Catalytic Cracking with 93% FCC ECAT+7% MM3 Additive

The catalyst of Example 2 comprised 7 wt % MM3 additive with 93 wt % FCCECAT. Catalytic cracking reactions of VGO at reactor temperature of 530°C., constant injection time of 30 seconds and cat/vacuum-gas-oil ratiosof 3.0, 3.9, 4.8 and 6 wt/wt are studied to see the effect. Propyleneand liquid olefin content are shown in Table 5.

TABLE 5 Product composition from Example 2 Catalyst ECAT + MM3 additive(93 wt % + 7 wt %) Feed VGO Cracking Temperature, 530.0 530.0 530.0530.0 ° C. Catalyst to vacuum- 3.00 3.90 4.80 6.00 gas-oil ratio, wt/wtConversion, wt % 67.81 70.07 72.92 75.39 YIELDS, wt %: Coke 2.84 3.214.19 5.86 Dry Gas (H₂, C₁-C₂) 3.09 3.57 3.99 4.25 LPG 24.83 27.55 28.2029.09 Propylene 9.31 9.95 9.45 9.31 Butylenes 8.73 9.14 8.37 8.21Gasoline (C₅-216° C.) 36.35 35.14 35.86 35.60 LCO (216-370° C.) 20.2319.51 18.24 17.07 Unconverted (above 12.66 11.03 9.52 8.13 370° C.) %Liq. Olefins 36.57 28.80 25.62 21.11 % Reduction of liq. −14.28 −6.67−2.48 −5.45 Olefins % Aromatics 30.31 42.53 46.65 52.07 % Increase in−7.844 13.444 17.654 13.715 Aromatics RON 83.5 98 100.6 101.5 Increasein RON Units −11.400 1.900 3.400 3.100

Propylene yield obtained with 7 wt % MM3 additive in ECAT is in therange of 9.3 wt % to 9.95 wt %. ΔLPG yield obtained compared toExample-1 is 5.5 wt % to 5.8 wt %. However, this additive is cokeselective compared to Example-1 and A coke reduction is by 0.5 wt % to0.6 wt %. An increase in the yields of aromatics in the range of 13.44%to 17.65% and in the RON units in the range of 1.9 to 3.4 units wasobserved.

Example 3: Catalytic Cracking with 85 wt % FCC ECAT+15 wt % MM3 Additive

The catalyst of Example 3 comprised 15 wt % MM3 additive with 85 wt %FCC ECAT. Catalytic cracking reactions of VGO at reactor temperature of530° C., constant injection time of 30 seconds and cat/oil ratios of3.0, 3.9, 4.8 and 6 wt/wt are studied to see the effect. Propylene andliquid olefin content are shown in Table 6.

TABLE 6 Product composition from Example 3 Catalyst ECAT + MM3 additive(85 wt % + 15 wt %) Feed VGO Cracking Temperature, 530.0 530.0 530.0530.0 ° C. Catalyst to vacuum- 3.00 3.90 4.80 6.00 gas-oil ratio, wt/wtConv., wt % 68.23 71.20 72.70 75.74 YIELDS, wt %: Coke 3.05 3.24 4.215.90 Dry Gas (H₂, C₁-C₂) 3.48 4.13 4.58 5.26 LPG 26.92 29.92 30.71 32.73Propylene 10.24 10.69 10.22 11.63 Butylenes 9.68 9.85 9.20 9.77 Gasoline(C₅-216° C.) 34.11 33.25 32.63 31.86 LCO (216-370° C.) 19.96 18.32 17.9416.61 Unconverted (above 12.48 11.13 9.92 7.65 370° C.) % Liq. Olefins36.30 27.69 21.74 17.39 % Reduction of liq. −13.44 −2.56 13.04 13.14Olefins % Aromatics 36.9 47.32 31.22 27.71 % Increase in 12.19 26.22−21.26 −39.49 Aromatics RON 98.8 100.4 94.6 89.6 Increase in RON Units3.90 4.30 −2.60 −8.80

Propylene yield obtained with 15 wt % additive in ECAT is in the rangeof 10.2 to 11.6 wt %, which gives an increase by 4.0 wt % to 4.7 wt %.ΔLPG yield obtained compared to Example-1 is 7.6 wt % to 9.4 wt %.However, this additive is coke selective compared to Example-1 and Δcokereduction is by 0.6 wt. It is found that, using the catalyst compositionof the present disclosure, an increase in the propylene yield and in thebutylene yield, is obtained in the resultant product, as compared tothose of the base catalyst FCC SCAT. This was also accompanied by areduction in liquid olefin content and the coke yield, especially athigher catalyst to vacuum-gas-oil ratios.

Technical Advances and Economical Significance

The present disclosure described herein above has several technicaladvantages including, but not limited to, the realization of:

-   -   A catalyst composition comprising an additive for an FCC process        that provides a product having increased propylene and butylene        yields and reduced liquid olefin content; reduced coke yields;        with an increase in aromatic yields and the increase in RON        units;    -   an FCC process that is more profitable; and    -   an FCC process that causes reduced fouling of the reactors.

The foregoing description of the specific embodiments will so fullyreveal the general nature of the embodiments herein that others can, byapplying current knowledge, readily modify and/or adapt for variousapplications such specific embodiments without departing from thegeneric concept, and, therefore, such adaptations and modificationsshould and are intended to be comprehended within the meaning and rangeof equivalents of the disclosed embodiments. It is to be understood thatthe phraseology or terminology employed herein is for the purpose ofdescription and not of limitation. Therefore, while the embodimentsherein have been described in terms of preferred embodiments, thoseskilled in the art will recognize that the embodiments herein can bepracticed with modification within the spirit and scope of theembodiments as described herein.

Throughout this specification the word “comprise”, or variations such as“comprises” or “comprising”, will be understood to imply the inclusionof a stated element, integer or step, or group of elements, integers orsteps, but not the exclusion of any other element, integer or step, orgroup of elements, integers or steps.

The use of the expression “at least” or “at least one” suggests the useof one or more elements or ingredients or quantities, as the use may bein the embodiment of the disclosure to achieve one or more of thedesired objects or results.

Any discussion of documents, acts, materials, devices, articles or thelike that has been included in this specification is solely for thepurpose of providing a context for the disclosure. It is not to be takenas an admission that any or all of these matters form a part of theprior art base or were common general knowledge in the field relevant tothe disclosure as it existed anywhere before the priority date of thisapplication.

The numerical values mentioned for the various physical parameters,dimensions or quantities are only approximations and it is envisagedthat the values ten percent higher/lower than the numerical valuesassigned to the parameters, dimensions or quantities fall within thescope of the disclosure, unless there is a statement in thespecification specific to the contrary.

While considerable emphasis has been placed herein on the components andcomponent parts of the preferred embodiments, it will be appreciatedthat many embodiments can be made and that many changes can be made inthe preferred embodiments without departing from the principles of thedisclosure. These and other changes in the preferred embodiment as wellas other embodiments of the disclosure will be apparent to those skilledin the art from the disclosure herein, whereby it is to be distinctlyunderstood that the foregoing descriptive matter is to be interpretedmerely as illustrative of the disclosure and not as a limitation.

The invention claimed is:
 1. An additive for a catalyst composition fora fluid catalytic cracking process comprising a zeolite impregnated withphosphorus in an amount of 12 wt % with respect to the weight of saidzeolite and a combination of metal promoters comprising only nickel andcalcium, independently in the range of 0.5 wt % to 2.0 wt % with respectto the weight of said zeolite.
 2. The additive as claimed in claim 1,wherein a precursor of phosphorus is at least one phosphorus compoundselected from the group consisting of phosphoric acid, phosphates,phosphorous acid, phosphites, pyrophosphoric acid, pyrophosphates,polymeric phosphoric acid, polyphosphates, metaphosphoric acid andmetaphosphates.
 3. The additive as claimed in claim 1, wherein an amountof said metal promoters with respect to the weight of said zeolite are:a. 1.0 wt % nickel; and b. 1.0 wt % calcium.
 4. The additive as claimedin claim 1, wherein a precursor for each of said metal promoter is anitrate salt of said respective metal.
 5. The additive as claimed inclaim 1, wherein said zeolite is at least one selected from the groupconsisting of ZSM-5, ZSM-11, ZSM-12, ZSM-48, ZSM-57, SAPO-5, SAPO-11,SAPO-17, SAPO-18, SAPO-34, SAPO-44, MCM-22, zeolite-Y and zeolite-Beta.